1. Field of the Invention
The present invention relates to a vehicle control system which connects and cooperatively operates a plurality of control devices.
2. Description of the Related Art
Conventionally, as disclosed, for example, in Japanese Unexamined Patent Application, First Publication, No. Hei 7-7504, a vehicular LAN which connects together a plurality of electric control devices that are mounted in a vehicle is known.
In this vehicular LAN, a plurality of electronic control units (ECUs) send sensor data to one control operating communication unit, and the control operation communication unit carries out operations based on the received data, returns control signals to each of the electronic control units, and thereby a network having what is termed a server-client relationship is formed.
In the vehicular LAN according to the one example of the conventional technology described above, there are cases in which, when electrical equipment such as an actuator, which is an controlled object connected to the plurality of electronic control units, is modified, the type of the operation command values output in order to direct the operation of the controlled object also changes.
Accompanying this, when the processing content of each of the electronic control units is modified, and in particular, in the case that a plurality of electronic control units are controlled so as to operate cooperatively, there is the concern that the processing content of other electronic control units having controlled objects that have not changed will also have to be changed.
Furthermore, the control signal that controls the operation of the controlled object is calculated in the control operation communication unit, and thus in the control operation communication unit, there are cases in which the reading device for receiving and reading each of the types of data output from the modified controlled object, the conversion device that converts the received data to a predetermined variable format that is used in the control operation, and the like, must be newly provided, or that the content of the control operation must be changed in conformity with the format of the received data.
In particular, as in a fuel cell vehicle, for example, in a system in which the types of the control signals sent and received between a control operation communication unit and a plurality of electronic control devices or controlled objects, when the type of these control signals must also be changed along with modifications in the controlled objects, the problem occurs that updating and improvement of the control system requires complicated labor. This is the first problem.
In addition, in a vehicular LAN according to the one example of the conventional technology described above, in the case that data is sent to the control operation communication unit from the plurality of electronic control units, a method is known in which data is partitioned into variable length packets and then sent in order to improve the transmission efficiency.
However, when the packet length is made large in order to improve the transmission efficiency, the problem occurs that the necessary waiting time until the completion of the transmission of one packet becomes long, and thereby the communication delay time becomes long and the responsiveness of the control system deteriorates. This is the second problem.
Furthermore, in such a vehicular LAN, when damage occurs on the network that connects the control operation communication unit and the plurality of electronic control units, there is a concern that a chain of damage or failure in the system as a whole will occur. Thus, a method is known in which redundancy is provided in order to maintain functionality during the occurrence of damage that is equivalent to that during normal operation by introducing redundancy into the network.
However, in the vehicular LAN according to the one example of the conventional technology described above, the redundant system duplicates, so to speak, the operational network structure used during normal operation, and the redundant system is used after switching from the operational system on which damage has occurred. This devices that when the operational network is operating normally, the network of the redundant system is not used to send or receive data, and in the case that the damage occurs, data identical to the data sent and received by the operational network is sent and received by the network of the redundant system.
Thus, during normal operation of the operational network, the problem occurs that the network of the redundant system cannot be effectively used. Furthermore, because the network of the redundant system is formed simply by duplicating the operational network structure, the scale of the vehicular control system as a whole increases, and there is the problem that the costs when constructing the vehicular control system balloon. This is the third problem.